Magellan NAV Companion for Palm/OS (magnav)

This format can...

read and write waypoints

Magellan NAV Companion for Palm/OS is not really designed
for this sort of use, but its file format is supported and with a
little bit of patience you can both read and write NAV Companion
waypoints. This conversion is based on
partially incomplete reverse-engineering of the record format, so it
may not work with all versions of NAV Companion. It has been tested
with version 2.10 and 3.20.

Translating NAV Companion waypoints to another format is as easy
as with any other format. Just find the Companion_Waypoints database
in your palm backup directory and use it as the input file.

When translating waypoints back to NAV Companion, though, you need
to jump through some hoops:

First, you must merge any waypoints that already exist in the database
in your Palm Backup directory with the ones you are adding; failure to
do so will result in only the new points being available in NAV Companion,
even if you give the new database a different name (it will overwrite
the old database, even in your backup directory. That's a feature of
PalmOS, not of NAV Companion.)

Second, you must use the installer to install your new PDB file. Don't
make the mistake of copying it over the existing Companion_Waypoints.PDB
file; the one on the handheld will overwrite it rather than merging with
it.

Finally, because NAV Companion is not designed to work with desktop
applications, you must tell NAV Companion that its waypoints database
has changed out from under it. One way to do this is to go to the
waypoints screen and attempt to scroll; that will force it to reread
the database and fix the record pointers that it keeps on the heap.